Amyloidoses are clinical disorders caused by deposition of insoluble fibrils, derived from misfolding and aggregation of a soluble protein. Beta2-microglobulin is a globular amyloidogenic protein responsible for dialysis related amyloidosis (DRA), a severe complication that occurs in patients undergoing chronic hemodialysis. [1]. The first natural variant of beta2-microglobulin (D76N), recently discovered, is instead responsible for a hereditary amyloidosis. [2]. The aggregation process of beta2-microglobulin monomer into fibrils is a complex and still uncertain mechanism where protein misfolding is a key event. A characterization of partially structured intermediates of a protein folding has relevant interest as such species play a significant role in the fibrillogenesis. Interestingly, one of the two intermediates of the folding pathway of beta2-microglobulin (known as I2), is significantly populated under physiological conditions and is more aggregation-prone. As I2 slowly interconverts into the native form (N), a CE method previously afforded the monitoring of N and I2 at equilibrium. CE results also showed that the values of free energy of unfolding are correlated to the population of these intermediate conformers. [3]. Based on these data, CE is herein used to characterize copopulated conformational ensembles of beta2-microglobulin variants known to have different amyloidogenicity. Several isoforms have been selected, including full-length and truncated beta2-microglobulin identified in DRA amyloid deposits, isoforms artificially created for stability studies and the new D76N. These proteins are analyzed by CE and HR-MS. The mass spectra provide important information, as each spectrum is characterized by its own m/z CSD which corresponds to different conformations at equilibrium. [4].

Characterization of different variants of beta2-microglobulin by capillary electrophoresis and high-resolution mass spectrometry

BERTOLETTI, LAURA;COLOMBO, RAFFAELLA;DE LORENZI, ERSILIA
2014

Abstract

Amyloidoses are clinical disorders caused by deposition of insoluble fibrils, derived from misfolding and aggregation of a soluble protein. Beta2-microglobulin is a globular amyloidogenic protein responsible for dialysis related amyloidosis (DRA), a severe complication that occurs in patients undergoing chronic hemodialysis. [1]. The first natural variant of beta2-microglobulin (D76N), recently discovered, is instead responsible for a hereditary amyloidosis. [2]. The aggregation process of beta2-microglobulin monomer into fibrils is a complex and still uncertain mechanism where protein misfolding is a key event. A characterization of partially structured intermediates of a protein folding has relevant interest as such species play a significant role in the fibrillogenesis. Interestingly, one of the two intermediates of the folding pathway of beta2-microglobulin (known as I2), is significantly populated under physiological conditions and is more aggregation-prone. As I2 slowly interconverts into the native form (N), a CE method previously afforded the monitoring of N and I2 at equilibrium. CE results also showed that the values of free energy of unfolding are correlated to the population of these intermediate conformers. [3]. Based on these data, CE is herein used to characterize copopulated conformational ensembles of beta2-microglobulin variants known to have different amyloidogenicity. Several isoforms have been selected, including full-length and truncated beta2-microglobulin identified in DRA amyloid deposits, isoforms artificially created for stability studies and the new D76N. These proteins are analyzed by CE and HR-MS. The mass spectra provide important information, as each spectrum is characterized by its own m/z CSD which corresponds to different conformations at equilibrium. [4].
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/11571/981671
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